海河干流流域暴雨径流非点源污染负荷解析与控制策略

随着点源污染逐渐得到有效控制,非点源污染对海河干流流域水环境污染的贡献日益增大,对其污染负荷进行科学测算成为海河干流水质达标方案制订的重要前提。基于GIS技术,通过土地利用类型划分,利用PLOAD模型对海河干流的暴雨径流非点源污染负荷进行了计算。结果表明,海河干流流域建设用地的比例依海河流向自上而下逐渐递减,而涉农用地逐渐增加,城区地表径流与农业面源污染分别是上、下游地区重要的非点源污染负荷来源。关于流域的暴雨径流非点源污染负荷,CODCr为15 619.29 t/a,NH3-N为369.16 t/a,TN为851.20 t/a,TP为250.29 t/a。为改善海河干流水质,非点源污染控制应纳入流域的污染物总量控制计划中,与点源污染一起参与环境容量的分配与控制。

Analysis of the non-point source pollution load from the storm runoff and its control strategy for Haihe River trunk stream,Tianjin

This paper is aimed at making an integrated calculation and investigation of the non-point source pollution load caused by the storm runoff for Haihe River trunk stream,Tianjin,based on the GIS technology and the categorization of different land-uses via the PLOAD model.As is known,with the point source pollution gradually being effectively controlled,the non point source pollution load has become the key factor to result in or prepare for the Haihe River trunk stream water management plan.To solve the problem,the non point source pollution load from storm runoff for Haihe River trunk stream was calculated thtruough the PLOAD model plus migration risk for pollution migration.The said PLOAD model,comprises a GIS tool which can identify more accurately the land use types,and has been proved to be simpler and easier for application in comparison with the other similar ones.The results indicate that the percentage of construction land use reduces gradually from the upstream to the downstream of Haihe River trunk stream,while the percentage of agricultural land use increases.The urban runoff is the key source to the non-point source pollution of the upstream areas while the agricultural non-point pollution serves as the source for the downstream area pollution.As regards to the non-point source pollution load from the storm runoff for its trunk stream,it has been found that the load of CODCr,NH3-N,TN,TP for Haihe River trunk stream turn to be 15 619.29 t/a,369.16 t/a,851.20 t/a,250.29 t/a,respectively.For the difference in the runoff pollutant concentration ratios from the different land-use types,the high loss risk may not be definitely the chief contributor to the non-point source pollution load.Therefore,it is necessary to integrate the control of the runoff non-point source pollutions for the entire basin.Therefore,the paper suggests to improve the water quality of the River by controlling the entire pollution amount of the watershed by low impact development (LID) measures,sponge city construction and other technical measures in urban area,and by buffer zone's construction with the increase of proper pits,ponds,depressions in addition to well-planned vegetation.